Given you re-access to the theme. Kindly re-download the theme, activate some other theme, delete the old theme and upload and activate new theme.

Deletion of theme does not delete theme options or its settings. Uploading and activating the new theme will solve these problems.

In the updated theme you can use any other video plugin. All you have to do is go to Appearance>>Theme Option>>Slider Setting and you will find Other slider shortcode option. Paste the shortcode in that box.